What i would like to see- Mtbr.com
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  1. #1
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    What i would like to see

    What I would like to see

    Spherical bushings…

    I would like to be able to change the U bushings with spherical bushings. That way all those “twisting” forces that damage the rear shock would be eliminated!
    Yes.
    I can see that many new bikes include some kind of a “Y” link or a shock extender, but that is mainly for fitting reasons…

    Anyway,
    I’ve seen lots of shocks getting damaged by misalignment issues, between their mounts, so I guess that if the manufacturers were able to offer a spherical joint option, it would be just great!

    After all they are quite common in the motorbike universe...

    Just a thought.
    Attached Thumbnails Attached Thumbnails What i would like to see-fox001-00-004-a_1.jpg  

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  2. #2
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  3. #3
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    Quote Originally Posted by keen View Post
    Hey!
    Many thanks!

  4. #4
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    Spherical bearings, as mentioned in that other thread, start making noise very quickly. In cars, you can get away with them for shock mounts because they stay loaded in the same direction under most conditions as tires aren't leaving the ground as often. Bikes on the other hand are constantly loading and unloading the shock joints, every time that tire comes off the ground.

    I think MTB would be better off with a needle bearing embedded in an elastomer shell. The misalignment angle is very small as it's due to components flexxing, not actual designed articulation of the joint. The needle bearing will have lower friction than a spherical bearing (rolling vs sliding contact) and the elastomer would deal with the misalignment to reduce bending loads. Cars have done similar things with suspension bushings and often it provides a very good middle ground between noise and precision.

    It wouldn't work on a standard 15mm shock mount. But you might be able to come up with something on the newer bearing mount shocks with 25mm radial bearings. I don't get why they went with two radial bearings on those anyway over a needle bearing?

  5. #5
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    Yes we do need them

  6. #6
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    On the other hand, if the shock's eyelets would allow for a larger diameter spherical bushing (i would strongly suggest an IGUS polymer) all the "rattling" problems would fade away.
    Squeezing a tiny spherical at the same space were an (already small) plain bushing (DU) is resting, may cause problems.
    So,
    A shock with a pair of larger diameter IGUS spherical bushings, sounds an easy & safe way to avoid the problems caused upon the shock absorber by the suspension chassis flexing...

  7. #7
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    No we don't. Mounting between two eyelets gives plenty of give to deal with frame flex. Especially with IGUS bushings.

    But if you want to try Sphericals, just ream your shock eyelets out to 16mm and I'll sell you some. They've been used in the past by 5th Element, Ohlins, Cane Creek, DT and others on mtb. They were only needed for shocks like the Fox/specialized seatstay Brains and Merida LRS because the shock was mounted on a lean and pivoted in several directions as it compressed.

    But what we definitely don't need is trunnion shock mounts. That's the worst idea ever for shock life. We've only seen broken Fox shock shafts on Trunnion mount shocks.
    Owner of www.shockcraft.co.nz, Mech Engineer, Tuner, Manitou, Motorex, Vorsprung EPTC, SKF, Enduro
    www.dougal.co.nz

  8. #8
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    There are lots of seatstay-yoke bikes, revel is the newest one on the block (shouldn’t be as bad due to dual link design). The structure does give some added flexibility to the designer, with the negative being the side loads, which could be solved with spherical bearings. I don’t think most bike manufacturers give 2 ****s whether the shock holds up after a few seasons. This would help. Choose your frame carefully.
    "It's only when you stand over it, you know, when you physically stand over the bike, that then you say 'hey, I don't have much stand over height', you know"-T. Ellsworth

    You're turning black metallic.

  9. #9
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    My S-works Demo 8 had them on the Ohlins TTX. I got sick of replacing the rose joint every 2nd weekend through side loading. So Converted it to the traditional Pin/Bushing arrangement and noticed no performance difference however obtained complete reliability and silence.

  10. #10
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    Elastomeric mounts similar to traditional auto and moto shocks?
    Do the math.

  11. #11
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    Elastomers seem to cover that small side-to-side movement we are talking about. But the are out of fashion, mainly due to the performance myth of the needle bearing.

    My prototype bike (Full floating double action suspension system) has all links equipped with accetalon bushings. They held up for years of abuse...

    UncaJohn

  12. #12
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    Compared to DU bushings, the needle bearing is massively lower in friction. Enough that you will notice the difference while riding.

    Compared to the IGUS bushings, the needle bearing has less friction, but probably not enough to actually notice while riding.

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